JP2009048009A - Mirror device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mirror device capable of maintaining reflection characteristics of a mirror by preventing damage of the mirror (in particular, a mirror reflection face). <P>SOLUTION: In the mirror device having a plurality of (three or more) laminated substrates, one of a plurality of substrates is a mirror substrate having the mirror. The mirror is connected to the mirror substrate by a supporting member rotationally, and the mirror refection face and a frame are arranged on the same surface side of the mirror. The mirror is arranged in a closed space formed of the mirror substrate and other substrates constituting the mirror device. At least one of the a plurality of substrates is formed of at least partially optically transparent material, and through the optically transparent material part, the space outside the mirror device and the mirror are connected optically. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mirror device that reflects electromagnetic waves, millimeter waves, visible light, infrared light, ultraviolet light, or sound waves. Specifically, the present invention relates to a mirror device used in an optical communication system, a lighting device, or the like. More specifically, the present invention relates to a 1 × 2 optical switch, an ON / OFF optical switch, and a mirror device applied to an apparatus having them in an optical communication system.

  A mirror device has been proposed in which a mirror is operated using electrostatic driving to switch the propagation direction of an optical signal. In Patent Document 1, the mirror posture is defined using a substrate disposed above the mirror and a substrate disposed below the mirror. Specifically, the mirror switches the light propagation direction in a state where the mirror is simultaneously in contact with both the substrate above the mirror and the substrate below the mirror.

JP 2004-78136 A

In the above prior art, when the light propagation direction is switched, the mirror comes into contact with the substrate provided on the mirror at the mirror reflection surface. For this reason, when the switching operation is repeatedly performed over a long period of time, damage to the mirror reflection surface or dust generated by contact between the mirror and the substrate above the mirror may run on the reflection surface. As a result, there arises a problem that the reflection characteristics on the mirror reflection surface are deteriorated. Also, when the mirror reflecting surface is damaged by vibration or impact, the reflection characteristics are deteriorated.
The object of the present invention is to prevent damage to the mirror, particularly the mirror reflecting surface, when the switching operation is repeated over a long period of time or when the mirror position is forcibly displaced by vibration or impact. It is to provide a mirror device that maintains reflection characteristics.

In order to solve the above problems, a mirror device of the present invention includes a mirror that has a reflecting surface that reflects light and is held movably, and switches the direction in which the light is reflected.
A first substrate having an electrode for moving the mirror; a second substrate provided on the upper side of the first substrate; provided on the second substrate and the mirror; A third substrate having an opening to pass through, and a fourth substrate provided above the third substrate and transmitting the light,
The distance between the mirror and the third substrate is larger than the distance between the mirror and the first substrate.

Another mirror device of the present invention is a mirror device that includes a mirror that has a reflecting surface that reflects light and is held movably, and switches the direction in which the light is reflected.
A first substrate having an electrode for moving the mirror; a second substrate provided on the upper side of the first substrate; provided on the second substrate and the mirror; A third substrate to transmit,
The distance between the mirror and the third substrate is larger than the distance between the mirror and the first substrate.

Another mirror device of the present invention is a mirror device that includes a mirror that has a reflecting surface that reflects light and is held movably, and switches the direction in which the light is reflected.
An electrode having a reflection surface side substrate provided on the reflection surface side of the mirror and having an opening through which the light passes, and an electrode provided on the opposite side of the reflection surface of the mirror and applying a force for moving the mirror A substrate, and a transmission substrate that is provided so as to cover the opening of the reflection surface side substrate and transmits the light,
The distance from the reflective surface to the reflective surface side substrate is larger than the distance from the mirror to the reflective surface side substrate.

Another mirror device of the present invention is a mirror device that includes a mirror that has a reflecting surface that reflects light and is held movably, and switches the direction in which the light is reflected.
A reflective surface-side substrate that is provided on the reflective surface side of the mirror and transmits the light; and an electrode substrate that is provided on the opposite side of the reflective surface of the mirror and has an electrode that applies a force to move the mirror. Prepared,
The distance from the reflective surface to the reflective surface side substrate is larger than the distance from the mirror to the reflective surface side substrate.

Another mirror device of the present invention is a mirror device comprising a plurality of (three or more) substrates stacked,
One of the plurality of substrates is a mirror substrate having a mirror,
The mirror has a mirror reflection surface and a frame, and is rotatably connected to the mirror substrate and a support member.
The mirror reflecting surface and the frame are arranged on the same surface side of the mirror,
The other one of the plurality of substrates is a first substrate laminated on the side opposite to the mirror reflecting surface with respect to the mirror substrate,
Still another one of the plurality of substrates is a second substrate laminated on the mirror reflecting surface side with respect to the mirror substrate,
The mirror has a plurality (two or more) of stable operation postures,
The mirror is in contact with the first substrate at a plurality of positions opposite to the mirror reflecting surface of the mirror in the stable operation posture;
A distance between the mirror and the first substrate is larger than a distance between the frame and the second substrate;
The second substrate has a first stopper opening and a second stopper opening smaller than the first stopper opening;
The first stopper opening is larger than the mirror;
The second stopper opening is larger than the mirror reflecting surface and smaller than the mirror;
The mirror is disposed in a closed space formed by the plurality of substrates,
At least one of the plurality of substrates is partially or entirely made of a light transmissive member so as to optically connect the mirror outside the mirror device and the mirror.

  According to this configuration, since the mirror does not come into contact with other members on the side having the mirror reflection surface for a switching operation that is repeatedly performed over a long period of time, the mirror reflection surface can be prevented from being damaged or contaminated. As a result, the reflection characteristics of the mirror can be maintained for a long time. Furthermore, even when vibration or impact is applied to the mirror, the mirror does not come into contact with other members on the mirror reflection surface, so that the reflection characteristics of the mirror can be maintained. At the same time, the amount of deformation of the support member that connects the mirror to the mirror substrate can be limited, so that damage to the support member can be avoided and the function of the mirror can be maintained. Further, since the mirror is housed in the closed space, it is possible to prevent the entry of foreign matter from the outside, and the function of the mirror can be maintained for a long time.

  ADVANTAGE OF THE INVENTION According to this invention, the mirror device which prevents the breakage | damage of the mirror by switching operation | movement repeated repeatedly for a long term or a vibration and an impact, and maintains the reflective characteristic in a mirror reflective surface can be provided.

Next, an embodiment of a mirror device according to the present invention will be described with reference to FIGS. In addition, this invention is not necessarily limited to these Examples.
Prior to the description of the present invention, a preliminary examination example of the mirror device of the present invention will be described with reference to FIGS.

[Preliminary study example 1]
A preliminary study example of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a main part of a mirror device 100 to be preliminarily studied. FIG. 2A is a top view showing a state in which two mirror devices to be subjected to preliminary examination are arrayed. FIG. 1 corresponds to a cross-sectional view taken along the line AA ′ of FIG. A broken line in FIG. 2B shows a schematic shape of the back surface of the stopper substrate 103. A broken line in FIG. 2C indicates a schematic shape of the mirror substrate 102. The mirror substrate 102 is disposed under the stopper substrate 103. A broken line in FIG. 2D indicates a schematic shape of the electrode substrate 101. The electrode substrate is disposed under the mirror substrate 102.

  The mirror device is formed by forming a space in a substrate in which the electrode substrate 101, the mirror substrate 102, and the stopper substrate 103 are laminated in this order from the bottom, and disposing the mirror 106 in this space. The lowermost electrode substrate 101 has a pivot 107, and electrodes 104 a and 104 b on both sides of the pivot 107. A mirror substrate 102 is disposed on the electrode substrate 101. The mirror 106 is formed by processing the mirror substrate 102. Here, the connection relationship between the mirror 106 and the mirror substrate 102 will be described with reference to FIG. The mirror 106 has a movable axis, and has a pair of beams 123 along the movable axis. The pair of beams 123 are support members that support the mirror 106 with respect to the mirror substrate 102, and connect the mirror 106 to the mirror substrate 102 so as to be rotatable.

  A stopper substrate 103 is provided on the mirror substrate 102. The stopper substrate 103 has a thin substrate above the mirror 106 and forms a space for accommodating the mirror 106 together with the electrode substrate 101 and the mirror substrate 102. The mirror 106 includes the electrode substrate 101, the mirror substrate 102, and the stopper. The structure is surrounded by the substrate 103. In this preliminary examination, the stopper substrate 103 has the opening 131. However, as long as it does not depart from the spirit of the present invention, the opening is provided as shown in other preliminary examination examples, for example, the preliminary examination example 11. May not be a through hole.

  In this preliminary study example 1, the stopper substrate 103 is an example in which an opening is provided by processing a silicon wafer by anisotropic etching. The opening 131 has an inclination depending on the crystal orientation. The method for forming the opening 131 may be a method other than anisotropic etching, for example, dry etching. The light reflected by the mirror reflecting surface 106a passes through the opening 131 and propagates outside the mirror device. The light source of light reflected by the mirror reflecting surface 106a may be provided inside the mirror device or may be provided outside the mirror device. The opening 131 is made larger than the mirror reflecting surface 106a. The stopper substrate 103 has a stopper step 105 having such a size that the beam 123 is not broken when the frame 108 provided around the mirror reflecting surface 106 a comes into contact with the stopper substrate 103. A method for determining the level difference will be described later.

  FIG. 3A shows a plan view of the mirror 106 and the mirror substrate 102. The mirror 106 includes a substrate portion 106b, a frame 108, and a mirror reflecting surface 106a as constituent elements. Although the mirror 106 may be formed using various materials, an SOI (Silicon on Insulator) wafer is used in this preliminary study example. The beam 123 is manufactured by etching from the substrate portion 106b (see FIG. 1) side. At this time, the intermediate oxide film 106c (see FIG. 1) is used as an etching stop layer. It is desirable to create a plurality of mirrors 106 simultaneously from one wafer. In this case, each of the plurality of mirrors may form an independent mirror device, or a set of mirror devices may be formed with the plurality of mirrors arrayed. In any case, when a plurality of mirrors are simultaneously formed on a single wafer, the beam stiffness of each mirror differs if the thickness of the beam 203 is different. As a result, individual mirror characteristics change when the same external power, for example, drive voltage is supplied to the individual mirrors, which is not desirable in terms of suppressing characteristic variations. Here, manufacturing the beam 203 by using the silicon layer on one side of the SOI wafer means that the thickness variation management of the beam 203 can be performed by variation management of the silicon layer of the SOI wafer. This is effective for suppressing variation in characteristics.

  On the other hand, when the mirror 106 is heavy, it is necessary to increase the rigidity of the beam that supports the mirror 106, so that the voltage required for the mirror operation, that is, the drive voltage increases. Supplying a large drive voltage increases the load on the electric circuit, so the mirror 106 is reduced in weight to avoid this. Specifically, the mirror 106 is provided with a mirror processing step 106d that is thinner than other regions. A frame 108 thicker than the mirror processing step 106d is provided outside the mirror processing step 106d to maintain the rigidity of the mirror 106. Further, the frame 108 thicker than the mirror processing step 106d contributes to prevention of contact between the mirror reflecting surface 106a and the stopper substrate 103. Since the frame 108 functions as a stopper, an effect of preventing the beam 123, which is a mirror support member, from being damaged can be obtained.

  N (multiple) mirrors 106 may be arranged side by side to form a set of mirror devices. Regardless of the example shown in FIG. 3, the beam 123, which is a support member for connecting the mirror 106 to the mirror substrate 102, may increase or decrease the number of turns, or may be a straight beam.

  The power connection pads 121a and 121b (see FIG. 2) are pads for connecting to a device for applying a voltage. For example, the power connection pads 121a and 121b are connected to a device that performs wire bonding and supplies a voltage.

As shown in the plan view of FIG. 3B, the electrodes 104a and 104b of the electrode substrate 101 are disposed on both sides of the pivot 107, and are connected to the power supply connection pads 121a and 121b by wirings 124a and 124b. The electrodes, the power supply connection pads, and the wiring are formed on an insulating film (for example, SiO ₂ film) on the surface of the electrode substrate, thereby ensuring each insulation.

  Next, an example of a processing process of the stopper substrate 103, the mirror substrate 102, and the electrode substrate 101 in this preliminary study example will be described. The mirror device 100 is assembled after the stopper substrate 103, the mirror substrate 102, and the electrode substrate 101 are individually processed. It is desirable to process each substrate using photolithography. The stopper substrate 103 is processed by performing photolithography on both sides and simultaneously performing wet etching on both sides with an anisotropic etching solution, for example, a 40% aqueous solution of KOH. As the material of the stopper substrate 103, silicon is desirable because it is easy to process and the linear expansion coefficient is the same as that of the mirror when silicon is used as the base material of the mirror 106. By performing anisotropic wet etching using KOH or the like on the silicon substrate, the dimension management of the stopper substrate 103 can be performed with high accuracy. Moreover, the manufacturing method which wet-etches a silicon substrate from the both sides to the same depth has the effect of improving productivity.

  However, as a material for the stopper substrate 103, a semiconductor other than silicon, a metal such as aluminum or brass, glass, resin, or the like can be used. Further, it can be processed using isotropic wet etching, dry etching using various gases, micromachining, injection molding and molding.

  An SOI wafer was used for the mirror substrate 102. The pattern of the mirror 106 was formed on the SOI wafer by photolithography, and etching was performed from both sides to form the mirror 106. Further, the mirror reflecting surface 106a is formed by covering a multilayer film of titanium and gold in order to ensure adhesion with the mirror 106 and increase the reflectance with respect to the light used. The multilayer film was formed by sputtering in the order of titanium and gold so that titanium becomes a base (base). The metal film can be formed on the silicon wafer by, for example, vapor deposition or plating other than sputtering. The thin film serving as the gold base may be another metal such as chromium. Further, another metal such as platinum may be inserted between titanium and gold to form three or more layers. If the reflectance to light used is high, the surface may not be gold. For example, aluminum can be applied. In addition, a dielectric multilayer film may be used as long as the adhesion to the mirror 106 can be ensured and the reflectance to light used is high.

  The electrode substrate 101 is formed by performing anisotropic wet etching on a silicon substrate. Since anisotropic wet etching can process a plurality of wafers at the same time, it is excellent in productivity, and at the same time, it is excellent in uniformity of processing accuracy because it is a process utilizing the characteristics of crystals.

  The electrode substrate 101 shown in FIG. 1 has different heights in the portions in contact with the mirror substrate (mirror support protrusions 150a and 150b), the top of the pivot 107, and the formation surfaces of the electrodes 104a and 104b. These height differences are formed by performing anisotropic wet etching a plurality of times. In the first anisotropic wet etching, a difference in height is formed on the electrode substrate 101 between portions (mirror support protrusions 150 a and 150 b) in contact with the mirror substrate and the top of the pivot 107. In the second anisotropic wet etching, a difference in height is formed between the top of the pivot 107 and the surface on which the electrodes 104a and 104b are formed.

The electrodes 104a and 104b are formed by forming a thermal oxide film (SiO ₂ film) on the surface of the silicon wafer after the second anisotropic wet etching, then forming a chromium film as a base (underlying), and sputtering a gold film thereon. Formed by etching and removing unnecessary portions of the gold film and the chromium film. The thin film serving as the gold base (base) for the electrodes 104a and 104b may be other than chromium, for example, titanium, platinum, nickel, or a multilayer film thereof. In addition to sputtering, film formation of chromium or gold on a silicon wafer can be performed, for example, by vapor deposition or plating. For the formation of the electrodes 104a and 104b, methods such as ion milling and lift-off can be applied in addition to the etching described above. The wirings 124a and 124b and the power connection pads 121a and 121b may be formed simultaneously with the electrodes 104a and 104b.

  Further, another metal film such as a platinum film may be inserted between the chromium film and the gold film to form a multilayer thin film having three or more layers. The material used for the electrodes 104a and 104b may be a conductive metal capable of forming a thin film, such as copper, aluminum, platinum, titanium, cobalt, molybdenum, and tungsten. It is desirable that these metals do not melt or diffuse at high temperatures. This is because by using a material that does not melt or diffuse at a high temperature, the mirror device manufacturing process can include a high-temperature process, and the options for the manufacturing process can be expanded. For example, when the manufacturing process includes a step of using gold-tin (Au—Sn) solder, a film having a heat resistant temperature of about 300 ° C. or higher is used. As such a multilayer film structure, for example, a multilayer film structure in which titanium (Ti) is used for the base layer, nickel (Ni) is used for the intermediate layer, and gold (Au) is used for the outermost surface layer can be applied. The thickness of the electrodes 104a and 104b is preferably 1 μm or less in order to avoid contact between the mirror 106 and the electrodes 104a and 104b.

  The mirror device 100 is formed by combining all the substrates after the stopper substrate 103, the mirror substrate 102, and the electrode substrate 101 are processed. At this time, holes for positioning (holes similar to the holes 122 for positioning shown in FIG. 9) are formed in each substrate, and pins or the like having the same dimensions are inserted into the holes for positioning. Alignment can be performed. However, this assembling method is an example, and alignment of each substrate may be performed using another method. For example, alignment may be performed with the external dimensions of each substrate. Alternatively, each substrate may be aligned using a separately formed alignment mark (not shown).

  Next, the operation of this mirror device will be described with reference to FIG. FIG. 4 is a cross-sectional view when the mirror device of this preliminary examination example is driven. FIG. 4A is a diagram showing a state when the potential difference between the electrode 104b and the mirror 106 is larger than the potential difference between the electrode 104a and the mirror 106. FIG. At this time, the mirror 106 rotates around the beam 123 and moves toward the electrode substrate 101, and stops with the back side of the mirror 106 contacting the pivot 107 and the electrode substrate 101. In this state, the incident light 161 is reflected by the mirror reflecting surface 106 a and becomes reflected light 162.

  Here, the incident light 161 may be light traveling from the inside of the mirror device 100 toward the mirror reflecting surface 106a (not shown). That is, a structure having a light source in the mirror device 100 may be used. Alternatively, the reflected light 162 may be light reflected into the mirror device 100 (not shown). That is, a structure having a light receiver inside the mirror device 100 may be used. Since the mirror device fixes the mirror posture by bringing the back side of the mirror 106 into contact with the pivot 107 formed on the lower portion of the mirror and the electrode substrate 101, the mirror 106 is a stopper disposed on the upper portion of the mirror 106 when the posture of the mirror 106 is fixed. It does not contact the substrate 103.

  FIG. 4B is a diagram illustrating a state where the potential difference between the electrode 104 a and the mirror 106 is larger than the potential difference between the electrode 104 b and the mirror 106. When the magnitude relationship of the potential difference between the electrodes 104a and 104b and the mirror 106 is reversed, the mirror 106 operates in the direction opposite to that in FIG. 4A as shown in FIG. 4B, and the incident light 161 is moved in another direction. Reflect. The stopper substrate 103 is partially retracted from the stopper substrate surface by the stopper step 105 so that the mirror 106 and the stopper substrate 103 do not contact when the mirror 106 is stationary. That is, since there is no contact between the mirror 106 and another substrate on the mirror reflecting surface 106a side, the mirror reflecting surface 106a is hardly damaged or soiled even if the mirror is operated repeatedly.

  As described above, the mirror 106 is given a driving force by the electrodes 104a and 104b, and determines a position and an angle by contacting the electrode substrate 101 and the pivot 107 in a state of reflecting light. In addition, since the attitude | position of the mirror 106 is made by contact | abutting with the pivot 107 and the electrode substrate 101, it is excellent in the stability of an attitude | position unlike the case where a mirror is hold | maintained hollow. It is desirable to provide the stopper step 105 between the mirror substrate 102 and the stopper substrate 103 in consideration of the size of the mirror 106 and the shape of the beam 123.

  In this preliminary examination example, the material of the mirror 106 is single crystal silicon, the width of the beam 123 is 10 μm, the thickness is 10 μm, the length is 600 μm, and the number of times of bending of the beam on one side is six (here, FIG. In this example, the number of bends is counted as 4), the length of the mirror is 1700 μm, the width is 500 μm, the width of the mirror frame 108 is 50 μm, and the size of the mirror reflecting surface 106 a is 400 μm × 300 μm. The step 106d was 300 μm, and the thickness of the substrate part 106b was 10 μm. FIG. 6 shows the mirror displacement when the impact acceleration in the direction in which the mirror 106 operates on the stopper substrate 103 is applied to the mirror 106. For example, when an impact acceleration of 500 G is applied, the amount of displacement of the mirror is about 420 μm. When the impact acceleration is 470 G or more, the maximum principal stress of the beam reaches 1000 MPa (= 1 GPa) which is the fracture stress of silicon. Therefore, in order to avoid damage to the beam 123, it is desirable that the stopper step 105 be 560 μm or less.

  On the other hand, if the stopper step 105 is slightly larger than the mirror back surface step 109, the mirror 106 and the stopper substrate 103 collide even when a slight impact acceleration is applied. If the collision frequency between the mirror 106 and the stopper substrate 103 is high, the possibility that the mirror 106 or the stopper substrate 103 is damaged increases. Therefore, it is desirable that the collision frequency between the mirror 106 and the stopper substrate 103 is low. If the impact acceleration applied as a standard is expected to be 250 G, the mirror is displaced by 200 μm. Since it is desirable to prevent the mirror 106 and the stopper substrate 103 from coming into contact with this displacement, it is desirable that the stopper step 105 be 200 μm or more. In this preliminary study example, the stopper step 105 is about 260 μm.

  If the mirror 106 collides with the stopper substrate 103 many times, the mirror 106 may be damaged. In particular, when the mirror reflecting surface 106a directly collides with the stopper substrate 103, there is a possibility that the thin film formed as the reflecting film peels off. Alternatively, there is a possibility that silicon forming the mirror 106 is chipped to generate dust and contaminate the mirror reflecting surface 106a. When the thin film on the mirror reflecting surface 106a is peeled off or contaminated, the reflectance of the mirror reflecting surface 106a is lowered. That is, the reflection characteristics of the mirror device 100 are deteriorated. The mirror device 100 of this preliminary study example has a structure in which the stopper step 105 is larger than the mirror back surface step 109 so that the mirror 106 contacts the stopper substrate 103 only when excessive vibration and impact are applied from the outside. did. When excessive vibration and shock are applied to the mirror 106 from the outside, the bending stress applied to the beam 123 is suppressed within a specified range by restricting the range in which the stopper substrate 103 moves, and the beam 123 is damaged. To avoid. Further, as shown in the cross-sectional view of FIG. 5, the frame 108 collides with the stopper substrate 103 by making the width of the opening 131 of the stopper larger than the mirror reflecting surface 106a. With this structure, the mirror reflecting surface 106a is protected even when excessive vibration or impact is applied to the mirror 106, so that the possibility of thin film peeling or contamination of the mirror reflecting surface 106a is reduced, and the mirror reflecting surface 106a is reduced. Can be avoided. That is, it is possible to avoid a decrease in the reflection characteristics of the mirror device 100.

[Preliminary study example 2]
Another preliminary study example will be described with reference to FIG. Most of the preliminary study example is the same as the preliminary study example 1. However, it differs from the preliminary study example 1 in that the mirror reflection surface 206a is lower than the mirror frame 108. The mirror 206 shown in FIG. 7A is a mirror in which the mirror reflecting surface 206a is made lower than the mirror frame 108 by performing etching a plurality of times on one silicon layer of the SOI substrate used as the material of the mirror 206. is there. When the mirror device 200 receives vibration and impact from the outside, the mirror frame 108 comes into contact with the stopper substrate 103, but the mirror reflection surface 206a is protected, so that the reflection characteristics of the mirror 206 are not deteriorated.

Further, it is desirable that the mirror reflecting surface 206a be sufficiently lower than the frame 108 in anticipation of deformation such as warpage occurring in the mirror 206 due to vibration or impact. For example, as shown in FIG. 7B, the mirror 306 has a mirror reflection surface 306a formed on an active layer (substrate portion) 106b, that is, a silicon layer opposite to the frame 108, to form the mirror device 300. May be. The stopper substrate 303 is formed with an opening 331 wider than that in FIG.
In the case of FIGS. 7A and 7B, the opening 231 or 331 provided in the stopper substrate 103 or 303 may be smaller than the mirror reflecting surface 206a or 306a as long as it does not interfere with the incident light reflection.

[Preliminary study example 3]
Another preliminary study example will be described with reference to FIG. The mirror device 400 shown in FIG. 8 is a mirror device in which the material of the mirror substrate 402 is a single layer substrate that is cheaper than SOI, for example, a silicon substrate. In this preliminary examination example, a beam (not shown) of the mirror 406 is formed by performing etching for adjusting the thickness and etching for forming a shape on a single layer substrate which is a material of the mirror substrate 402. Here, as the etching for adjusting the thickness, for example, anisotropic wet etching using a 40% aqueous solution of KOH can be used, and as the etching for forming the shape, for example, dry etching can be used. The opening 431 provided in the stopper substrate 403 is larger than the mirror reflecting surface 116 a and smaller than the mirror 406. Thus, when excessive vibration and impact from the outside are applied to the mirror 406, the mirror side surface 407 and the stopper substrate 403 come into contact with each other, thereby preventing the mirror reflecting surface 406a and the beam 123 from being damaged.

[Preliminary study example 4]
Another preliminary study example will be described with reference to FIG. FIG. 9B is a diagram of the stopper substrate 503 provided with one common opening 531 common to all the mirrors in order to simplify the design of the opening of the stopper substrate 103. The structure other than the common opening 111 is the same as that of the stopper substrate 103 of the preliminary examination example 1. The stopper substrate 103 of the preliminary examination example 1 shown in FIG. 2 has the opening 131 for each mirror 106 as shown in FIG. 9A, but in this preliminary examination example, a plurality of mirrors have a common opening. A stopper substrate 503 using 531 was used.

  Here, instead of providing one common opening common to all the mirrors, several common openings common to some of the N mirrors may be provided. The common opening 531 is desirably smaller than the size in the longitudinal direction of the mirror, that is, the direction orthogonal to the movable axis, and desirably larger than the mirror reflecting surface 106a. Reference numeral 122 denotes a positioning hole.

[Preliminary examination example 5]
Another preliminary study example will be described with reference to FIG. A mirror device 600 shown in FIG. 10 is a mirror device in which cushioning materials 621 and 622 are provided at portions where the stopper substrate 103 and the mirror frame 108 are in contact with each other. The mirror 606 has a configuration in which an upper cushioning material 621 is added to the mirror 106. In this figure, a buffer material 621 and a mirror frame 108 upper buffer material 622 are provided on the lower surface of the stopper substrate 103. However, it does not matter which one of these. It is desirable that the buffer materials 621 and 622 have a smaller elastic modulus than the stopper substrate 103 and the mirror frame 108. The stopper substrate 103 is produced in the same manner as in the preliminary study example 1. Since processing is easy, a method of providing the buffer material 621 only on the stopper substrate 103 is desirable. Since the buffer materials 621 and 622 are desirably members that do not easily adhere to the mirror frame 108 and the stopper substrate 103, a material having a low surface energy, such as polyimide, can be used. Further, if a member that absorbs light is used for the buffer materials 621 and 622, unnecessary diffusion of scattering hole light can be prevented.

[Preliminary Study Example 6]
Another preliminary study example will be described with reference to FIG. A mirror device 700 shown in FIG. 11 is a mirror device in which a first stopper step 734 and a second stopper step 735 are provided on a stopper substrate 745. In the mirror device 700 of the present invention, the distance from the frame 108 to the stopper substrate 745 is defined by the first stopper step 734. The first stopper step 734 is made smaller than the second stopper substrate 735. Further, the first stopper opening 732 provided in the stopper substrate 745 is made larger than the mirror reflecting surface 106a. With this structure, when the mirror receives vibration and impact from the outside, the mirror frame 108 comes into contact with the first stopper step 734 provided on the stopper substrate 745, so that the mirror reflecting surface 106a is protected. At this time, the second stopper opening 733 provided in the stopper substrate 745 may be smaller than the mirror reflecting surface 106a as long as it does not prevent light from entering and reflecting. Instead of the first stopper step 734, a protrusion may be provided at a position where the stopper substrate 745 contacts the mirror frame 108.

[Preliminary study example 7]
Another preliminary study example will be described with reference to FIG. A mirror device 800 shown in FIG. 12 is a mirror device having an electrode substrate 101, a mirror substrate 102, a spacer 841, and a stopper substrate 842 as constituent elements. In the preliminary examination example 1 described above, the mirror reflecting surface 106a is protected by processing the surface of the stopper substrate 103 facing the mirror. In this preliminary examination example, the mirror reflecting face 106a is protected by using the spacer 841 and the stopper substrate 842. To do. With this configuration, the processing load on the stopper substrate can be reduced. The spacer 841 and the stopper substrate 842 can be made of silicon, other semiconductors, metals such as aluminum and brass, glass, and resin. However, when silicon is used as the main material of the mirror 106, linear expansion is achieved. It is desirable to use silicon having the same coefficient. The thickness of the spacer 841 is selected so that the distance 805 between the stopper substrate 942 and the mirror 106 is larger than the distance from the mirror 106 to the electrode substrate 101. Furthermore, it is desirable that the thickness is such that the mirror 106 and the stopper substrate 842 do not contact with each other under normal vibration or impact. The selection of the thickness is determined in the same procedure as in the case of the preliminary study example 1 with reference to FIG. The stopper substrate 842 is processed by (dry) etching or machining. The electrode substrate 101 and the mirror substrate 102 are produced by the same method as in the preliminary examination example 1. The opening 831 of the stopper substrate 842 is larger than the mirror reflecting surface 106.

[Preliminary examination example 8]
13A and 13B are partial views of mirrors 906 and 1006 each having a mirror substrate having a shape different from that of the above-described preliminary examination example as a mirror substrate applied to the mirror device of the present invention. In the mirror device using this mirror, elements other than the mirror shape are the same as those in any one of the preliminary examination examples 1 to 7 described above. A mirror 906 shown in FIG. 13A is a mirror having a structure in which a mirror reflection surface 906a and a mirror frame 908 are separated via a substrate portion 906b. With this structure, the mirror can be reduced in weight. In particular, the effect of the structure becomes more prominent as the mirror reflection surface 906a can be made smaller than the entire mirror 906.

  The mirror shape of the mirror device of the present invention may be the shape shown in FIG. 13B, for example. In the case of the dimensional ratio shown in FIG. 13A, the processing area is narrow at the gap portion between the mirror reflecting surface and the frame, and the processing area is wide at other portions. When the mirror reflecting surface 906a cannot be made very small with respect to the entire mirror 906, the difference in the processing area becomes severe, so that the processing uniformity is reduced between these portions. Deterioration of processing uniformity may make it difficult to realize the intended mirror shape, which is undesirable. The shape shown in FIG. 13B is an example in which a portion having a small processing area is not provided in order to ensure processing uniformity. The mirror having such a structure can reduce the weight of the mirror while maintaining the processing uniformity when the mirror reflecting surface 1006a cannot be made very small with respect to the entire mirror 1006.

[Preliminary examination example 9]
As a mirror 1106 applied to the mirror device of the present invention, FIG. 14 shows a partial view of a mirror having a mirror having a shape different from that of the preliminary examination example 1 described above. In the mirror device using this mirror, the mirror shape and the elements other than the pivot 107 and the electrodes 104a and 104b on the electrode substrate 101 are the same as those in any of the preliminary examination examples 1 to 7 described above.
A mirror 1106 shown in FIG. 14 is a mirror having a mirror shape deformed from a rectangle to a polygon. In FIG. 14, since the mirror reflecting surface 1016 and the mirror frame 1018 are made the same height, the method shown in any of the preliminary examination examples described above, for example, the stopper opening of the stopper substrate is made larger than the mirror reflecting surface 1016. The mirror reflecting surface 1016 is protected against vibration and impact. As long as the mirror reflection surface 1016 is protected against vibration and impact by the method shown in any of the above-described preliminary examination examples, the height relationship between the mirror reflection surface 1016 and the mirror frame 1018 is not limited. The shape of the mirror may be another polygon or a circle. The mirror device shown in the preliminary study example 1 is limited to two directions of stable light reflection, but the mirror device using the mirror of this preliminary study example has the number of polygon sides constituting the mirror, or According to the drive source for driving the mirror, in this preliminary study example, the reflection direction of a plurality of lights can be stably formed according to the number of drive electrodes.

[Preliminary examination example 10]
Another preliminary study example will be described with reference to FIGS. 15 (a) and 15 (b). A mirror device 1200 shown in FIGS. 15A and 15B is a mirror device in which a lid 1223 having an optically transparent member as a constituent element is disposed on the mirror substrate 102 using a spacer 841. The lid 1223 has the function of the stopper substrate 103 in the preliminary examination example 2. Other configurations are the same as those in the preliminary examination example 2. For example, the mirror 206 in this preliminary study example is a mirror as shown in the preliminary study 2 in order to prevent the lid 1223 and the mirror reflecting surface 206a from coming into contact when the mirror 206 is displaced upward due to excessive vibration or impact. A mirror 206 having a mirror reflecting surface 206a lower than the frame 108 is used. The stopper step 1205 between the frame 108 and the lid 1223 is the same as the step 105. By providing the lid, it is possible to prevent foreign matter from entering the mirror from the outside.

  FIG. 15B shows still another preliminary examination example. In the preliminary examination example shown in FIG. 15 (b), the lid 1323 having the mirror substrate 102 and the electrode substrate 101 as constituent elements and a metal such as aluminum or kovar or a ceramic such as alumina (metal on the surface). And a housing 1329 including a film formed thereon. By covering the entire surface, dust and dust can be prevented from entering the mirror device. At this time, if the end of the lid 1323 and the receiving portion 1324 are made of metal or a metal film is formed on the surface of the receiving portion 1324, both can be easily assembled by welding or the like. At this time, by maintaining the airtightness inside the housing 1329, it is possible to avoid deterioration of the mirror 106 due to intrusion of humidity from the outside. The assembly method is not limited to welding, and an adhesive or solder may be used.

  The mirror device of the present invention will be described below with reference to the above preliminary examination examples 1 to 10.

[Example 1]
A mirror device 1400 of the present invention will be described with reference to FIGS. Further, FIG. 3A and FIG. 18 are used for the description of the mirror substrate and the electrode substrate constituting the mirror device of the present invention. The mirror device 1400 of the present invention is a mirror device having a plurality of (three or more) stacked substrates as components. One of the plurality of substrates is a mirror substrate 102 having a mirror 106. The mirror 106 is connected to the mirror substrate 102 by a beam 123 which is a support member, and is rotatable with respect to an axis defined by the beam 123. The mirror 106 has a mirror reflecting surface 106 a and a frame 108, and the mirror reflecting surface 106 a and the frame 108 are arranged on the same surface side of the mirror 106. The mirror 106 is disposed in a closed space formed by the mirror substrate 102 and another substrate constituting the mirror device 1400, specifically, the electrode substrate 101, the stopper substrate 103, and the lid 1423.

  One of the plurality of substrates is a first substrate (electrode substrate) laminated on the opposite side of the mirror reflecting surface 106a with respect to the mirror substrate 102, that is, on the lower side in FIGS. 16 (a) and 16 (b). 101). One of the plurality of substrates is a second substrate (stopper substrate 103) stacked on the mirror reflecting surface 106a side, that is, the upper side in FIGS. 16A and 16B with respect to the mirror substrate. . The mirror 106 has a plurality (two or more) of stable operation postures. The stable state is the same as the state shown in FIG. 4 as a preliminary examination example. The mirror 106 contacts the first substrate (electrode substrate 101) at a plurality of locations on the opposite side of the mirror reflecting surface 106a of the mirror 106 in the stable operation posture.

  At this time, the distance between the mirror 106 and the first substrate (electrode substrate 101), that is, the mirror back surface step 109, is the distance between the frame 108 and the second substrate (stopper substrate 103), that is, the first substrate. It is larger than the stopper step 1434. Further, the second substrate (stopper substrate 103) has a first stopper opening portion 1432 and a second stopper opening portion 1433 smaller than the first stopper opening portion, and the first stopper opening portion 1432 is The second stopper opening 1433 is larger than the mirror 106 and larger than the mirror reflecting surface 106 a and smaller than the mirror 106. The lid 1423 is composed of an optically transparent member at least partially. The lid 1423 can be made of the same member as the stopper substrate 103 or can be formed integrally. The mirror 106 is optically connected to a space outside the mirror device 1400 of the present invention.

  Hereinafter, the mirror device 1400 of the present invention will be described in more detail. The mirror device 1400 of the present invention is similar to the structure in which the opening is not provided to the stopper substrate in the preliminary study example 1 described above or the mirror device described in FIG. As for the operation of the mirror device, the same operation as that described with reference to FIG. The distance relationship between the mirror and the stopper substrate is also determined by the procedure described with reference to FIG.

  In this embodiment, a lid 1423 is disposed above the mirror substrate 102 with a stopper substrate 103 interposed therebetween. The stopper substrate 103 has a function of ensuring a gap between the mirror substrate 102 and the lid 1423. The lid 1423 is partially or entirely made of an optically transparent material. The light reflected by the mirror reflecting surface 106 a passes through an area made of an optically transparent material of the lid 1423 and is emitted to the outside of the mirror device 1400. The light source of light reflected by the mirror reflecting surface 106a may be provided inside the mirror device or may be provided outside the mirror device. The optically transparent material can be selected depending on the wavelength of light used. For example, in the case of visible light, quartz, Pyrex (registered trademark), BK7, borosilicate glass, or the like is used. In the case of infrared light, a material such as silicon can be selected in addition to the above material examples. It is desirable to form an antireflection film on the front and back surfaces of the lid 1423 where light passes. By forming the antireflection film, more light reflected by the mirror reflecting surface 106a can be emitted to the outside of the mirror device 1400.

  An electrode substrate 101 is disposed below the mirror substrate 102. The mirror 106 is driven by generating a potential difference between the electrodes 104 a and 104 b formed on the electrode substrate 101 and the mirror 106. The posture of the mirror 106 during operation is a posture in which the vicinity of the center on the back side of the mirror 106 is in contact with the pivot 107 and the end portion of the mirror 106. The first stopper step 1434 formed on the stopper substrate 103 is larger than the mirror back surface step 109. Since the mirror 106 does not come into contact with the stopper substrate 103 on the mirror reflecting surface 106 a side during operation, even if the mirror 106 is operated repeatedly, the mirror reflecting surface 106 a is damaged or soiled due to contact between the mirror 106 and the stopper substrate 103. hard. As a result, it is possible to avoid a decrease in the reflectivity of the mirror reflection surface 106a, that is, a decrease in the reflection characteristics of the mirror 106.

  Further, by making the first stopper opening larger than the mirror 106 and making the second stopper opening 303 larger than the mirror reflecting surface 106a, the contact between the mirror 106 and the stopper substrate 103 when vibration or impact is applied. It is desirable to limit the part to the frame 108. At this time, since the mirror reflection surface 106a is protected, it is possible to avoid a decrease in reflectance due to damage or contamination of the mirror reflection surface 106a, that is, a decrease in reflection characteristics of the mirror 106. At this time, the second stopper opening 1433 may be smaller than the mirror reflecting surface 106a as long as it does not hinder the incoming and reflected light.

  Further, when vibration or impact is applied to the mirror 106, the frame 108 and the stopper substrate 103 remain in contact with each other, and the mirror 106 may become inoperable. Since the force that attracts the frame 108 and the stopper substrate 103 is an electrostatic force, a meniscus force, or an intermolecular force, an antistatic film or a hydrophobic film is formed on the portion where the stopper substrate 103 and the frame 108 are in contact, and the surface is It is desirable to roughen the surface. The antistatic film, the hydrophobic film, or the roughening of the surface may be formed on one of the stopper substrate 103 and the frame 108 or on both.

Note that a state in which the contact state is unintentionally maintained can also occur during normal mirror operation. In order to avoid this, an antistatic film 1465 is formed on the electrode substrate 101, the surface state is hydrophobized with a hydrophobic film (not shown), and the vicinity of the contact point with the mirror 106 is roughened regions (1455a, 1455b). It is desirable to apply one or a combination thereof.
The antistatic film 1465 is, for example, a conductive film connected (or grounded) to an external power source. At this time, the potential of the conductive film is made common with the potential of the mirror 106. The roughening of the electrode substrate is preferably incorporated in the process of forming the pivot 107 or the mirror support protrusion 1450 (or 1550) in order to prevent an increase in the number of processes. For example, when the pivot 107 and the mirror support protrusion 1450 (or 1550) are fabricated by anisotropic etching of Si (silicon) using a KOH aqueous solution, the micropattern is etched in the same process to roughen the electrode substrate. By appropriately reducing the minute pattern, the minute pattern is excessively etched. Eventually, the minute pattern cannot maintain the initial pattern shape and roughens the electrode substrate surface. In this case, it is desirable that the fine pattern dimension is about φ35 μm or less with respect to the height 18 μm of the mirror support protrusion 1450 (or 1550).

  Further, by forming the peeling spring 170 on the mirror 106, it is possible to effectively avoid maintaining an unintended contact state between the mirror 106 and the electrode substrate 101 during normal mirror operation. The peeling spring 170 is shown in FIG. When the mirror 106 comes into contact with the electrode substrate 101, the tip of the peeling spring 170 first comes into contact with the electrode substrate 101. Thereafter, when the peeling spring 170 is deformed, the end portion 180 of the mirror comes into contact with the electrode substrate 101 to define the posture of the mirror 106. When the posture of the mirror 106 is changed, the mirror end 180 is peeled from the electrode substrate 101 by the restoring force of the peeling spring 170 that has been deformed. At this time, the end 180 of the mirror with high rigidity defines the mirror attitude, but the peeling spring 170 with low rigidity does not participate in the definition of the mirror attitude, so that the attitude of the mirror 106 can be kept stable.

  Furthermore, it is desirable to integrally form the stopper substrate 103 and the lid 1423 from the same member because the bonding process of both is reduced. A mirror device 1500 using such a stopper substrate is shown in FIG. The stopper substrate 103 and the lid are integrally formed by, for example, silicon multistage etching. At this time, a first stopper step 1534 and a second stopper step 1535 are formed on the stopper substrate 103. The first stopper step 1534 is larger than the mirror back surface step 109. Since the mirror 106 does not contact the stopper substrate 103 on the mirror reflecting surface 106a side during operation, the mirror reflecting surface 106a is not easily damaged or soiled due to the contact between the mirror 106 and the stopper substrate 103 even when the mirror 106 is operated repeatedly. . As a result, it is possible to avoid a decrease in the reflectivity of the mirror reflection surface 106a, that is, a decrease in the reflection characteristics of the mirror 106.

  Further, the distance from the frame 108 to the stopper substrate 103 is defined by the first stopper step 1534, the first stopper opening is made larger than the mirror 106, and the second stopper opening 1533 is made larger than the mirror reflecting surface 106a. Thus, it is desirable to limit the contact portion between the mirror 106 and the stopper substrate 103 to the frame 108 when vibration or impact is applied. At this time, since the mirror reflection surface 106a is protected, it is possible to avoid a decrease in reflectance due to damage or contamination of the mirror reflection surface 106a, that is, a decrease in reflection characteristics of the mirror 106. At this time, the second stopper opening 1533 may be smaller than the mirror reflecting surface 106a as long as it does not hinder the incoming and reflected light.

  Further, when vibration or impact is applied to the mirror 106, the frame 108 and the stopper substrate 103 remain in contact with each other, and the mirror 106 may become inoperable. Since the force that attracts the frame 108 and the stopper substrate 103 is an electrostatic force, a meniscus force, or an intermolecular force, an antistatic film or a hydrophobic film is formed on the portion where the stopper substrate 103 and the frame 108 are in contact, and the surface is It is desirable to roughen the surface. The antistatic film, the hydrophobic film, or the roughening of the surface may be formed on one of the stopper substrate 103 and the frame 108 or on both.

  The mirror 106 is desirably disposed in a space (closed space) closed by the electrode substrate 101, the mirror substrate 102, the stopper substrate 103, and the lid 1423. The closed space is formed by bonding the electrode substrate 101, the mirror substrate 102, the stopper substrate 103, and the lid 1423 (however, as described above, the stopper substrate 103 and the lid 1423 may be the same substrate). As the bonding method, bonding using a bonding agent such as solder, low-melting glass, or adhesive, direct substrate bonding such as anodic bonding or eutectic bonding can be applied. In the case of bonding using a bonding agent such as solder, low-melting glass, or adhesive, it is desirable to form a bonding material accommodation groove (not shown) in the bonding portion. The bonding material accommodation groove makes the bonding agent layer uniform by containing an excessive bonding agent. By homogenizing the bonding agent layer, the stability of bonding is improved, and deformation such as warpage of the bonded substrates can be suppressed.

  The bonding material accommodation groove is preferably formed without applying a process load to the substrates to be bonded. For example, in the mirror substrate 102 in which the beam 123 is formed on the thin Si layer side of the SOI substrate and the thin Si layer side is bonded to the electrode substrate 101, the beam 123 and the bonding material accommodation groove can be formed in the same process. desirable. At this time, if the thickness of the thin Si layer of the SOI substrate is 10 μm and the beam 123 is formed by dry etching in which the intermediate oxide film of the SOI substrate functions as an etch stop layer, the joint material prepared at the same time is accommodated. The depth of the groove is 10 μm. That is, in this structure, it is desirable that the bonding agent accommodation groove is formed on the mirror substrate 102 side.

  On the other hand, a protrusion (mirror support protrusion 1450) for supporting the mirror substrate 102 is formed on the electrode mirror substrate 101, and the electrode wiring is placed over the protrusion. When the electrode substrate 101 and the mirror substrate 102 are bonded on the insulating film after the wiring is covered with the insulating film, in the mirror device, the bonding material receiving groove is formed on the protrusion. Since the wiring is formed across the groove, the risk of problems such as disconnection or short circuit of the wiring is increased, which is not desirable. Further, in bonding the mirror substrate 102 and the stopper substrate 103, it is desirable to form the bonding material accommodation groove simultaneously with the step of forming the first stopper step or the second stopper step on the stopper substrate 102. For example, when the stopper substrate 103 is made of a single crystal Si substrate and the first stopper step or the second stopper step is formed by anisotropic etching, the bonding material accommodation groove is created simultaneously with the anisotropic etching. Thus, the bonding layer accommodation groove can be created without increasing the process load. In this case, if the depth of the bonding material accommodation groove is equal to or less than the first stopper step or the second stopper step, the depth of the bonding material accommodation groove can be controlled by the width of the bonding material accommodation groove.

  When the bonding material is solder bonding, bonding is performed by applying a bonding material such as gold-tin (Au-Sn) solder to the bonding portion and heating and pressing the substrates to be bonded. The solder layer formed by applying solder may be present on one of the substrates to be joined. The solder layer may be formed on either side of the substrate to be joined. However, the mirror substrate 102 is more fragile than the electrode substrate 101 and the stopper substrate 103. Therefore, the electrode substrate 101 and the mirror substrate 102 are joined to the electrode substrate 101 side. It is desirable to form a solder layer and form a solder layer on the stopper substrate 103 side in joining the stopper substrate 103 and the mirror substrate 102. However, it is desirable to form a solder base metal layer at the joint portion of the mirror substrate 102 in order to increase the adhesiveness of the solder.

  Furthermore, it is desirable to electrically connect the mirror to an external device using a solder layer or a base metal layer of the solder. For example, when the mirror is an electrostatic drive mirror, it is necessary to control or make the potential of the mirror constant. At this time, for example, a mirror disposed in a closed space is electrically connected to the mirror substrate 102, the mirror substrate 102 and the solder layer are electrically connected, and the solder layer or the underlying metal layer of the solder is connected to the electrode substrate 101. The mirror can be electrically connected to an external device by being electrically connected to the electrode formed in the above. The structure facilitates electrical connection to the mirror. As long as the solder layer or the underlying metal layer of the solder is exposed on the surface of the mirror device, the electrode formed on the electrode substrate 101 may not be connected to the solder layer or the underlying metal layer of the solder. Absent.

  The closed space containing the mirror is desirably hermetically sealed. More preferably, the closed space is sealed in a dry atmosphere or in a vacuum state. By sealing the closed space in a dry atmosphere or in a vacuum state, it is possible to avoid mirror operation failure due to moisture aggregation at the contact point between the mirror and the electrode substrate 101.

  The mirror device having such a configuration can avoid breakage or contamination of the mirror reflecting surface because the mirror does not come into contact with other members on the side having the mirror reflecting surface in response to repeated operations over a long period of time. As a result, the reflection characteristics of the mirror can be maintained for a long time. Furthermore, even when vibration or impact is applied to the mirror, the mirror does not come into contact with other members on the mirror reflection surface, so that the reflection characteristics of the mirror can be maintained. At the same time, the amount of deformation of the support member that connects the mirror to the mirror substrate can be limited, so that damage to the support member can be avoided and the function of the mirror can be maintained. Further, since the mirror is housed in the closed space, it is possible to prevent the entry of foreign matter from the outside, and the function of the mirror can be maintained for a long time.

  The electrode substrate 101, the mirror substrate 102, the stopper substrate 103, and the lid are formed in batches on separate wafers, integrated in a wafer state (wafer level packaging), and then individually separated by a method such as dicing, etching, or polishing. It is desirable to separate. For this purpose, the electrode substrate 101, the mirror substrate 102, the stopper substrate 103, and the lid have a common arrangement pitch. The electrode substrate 101, the mirror substrate 102, the stopper substrate 103, and the wafer on which the lid is formed can be sequentially bonded one by one, or a plurality of wafers can be bonded simultaneously.

  Here, an example in which dicing is used as a method of dividing the mirror device into pieces and securing the space on the power connection pads 121a and 121b will be described with reference to FIGS. As described above, it is desirable that the mirror device is integrated in the wafer state and then separated. The mirror device of the present invention has electrodes 104a and 104b for driving the mirror 106 on the electrode substrate 101 and power connection pads 121a and 121b for supplying voltage to the electrodes from the outside. Since the electrode is located in the closed space and the power supply connection pads 121a and 121b are located outside the closed space, the electrode and the power supply connection pad are connected using multilayer wiring or through wiring. When the power connection pads 121a and 121b are connected to an external power source by wire bonding, it is necessary to secure a space on the power connection pads 121a and 121b. At this time, it is necessary to exclude the mirror substrate 102, the stopper substrate 103, and the wafer on which the lid is formed from above the power connection pads 121a and 121b to secure a space.

  Dicing is performed three times to separate the mirror device. In the first dicing step, the position from the power supply connection pads 121a and 121b or the inner side thereof, that is, the side where the mirror exists is defined as a dicing line 306 and the cover to the mirror substrate 102 are cut. In this step, the dicing blade must not cut the power connection pads 121a and 121b or the wirings 124a and 124b (see FIG. 2) formed on the surface of the electrode substrate 101. The gap between the dicing blade and the power supply connection pads 121a and 121b or the wirings 124a and 124b in the first dicing step is the height of the mirror support protrusion 1450 or 1550 of the electrode substrate 101 in contact with the mirror substrate 102 in FIG. Given by

  Here, workability improves as the gap between the dicing blade and the power connection pads 121a and 121b or the wirings 124a and 124b increases. In order to enlarge the gap, it is desirable to form a dicing groove along the dicing line on the surface of the mirror substrate 102 facing the electrode substrate 101. FIG. 17A illustrates the dicing groove 241 using a cross-sectional view of the mirror substrate 102.

  More preferably, the groove is a dicing through hole 242 that penetrates the mirror substrate 102. In this case, since the load such as vibration and impact on the mirror 106 in the first dicing step is reduced, the risk of mirror breakage during dicing is reduced. The dicing through-hole 242 is illustrated in FIG. More preferably, a through hole similar to the dicing through hole is formed in the stopper substrate 103 and the lid 223. In this case, since the first dicing process is not necessary, the working efficiency is further improved. For example, in the case of a mirror device in which a stopper substrate 103 and a lid are integrated using a silicon substrate as a material, a dicing through hole of the stopper substrate 103 can be manufactured by anisotropic wet etching. In this case, the processing dimension management of the dicing through hole of the stopper substrate 103 is easy.

  In the second dicing process, a position outside the power connection pads 121a and 121b is used as a dicing line 307 to cut from the lid to the electrode substrate 101. Here, the mirror substrate 102, the stopper substrate 103, and the lid are formed with dicing through holes having a width that does not require the first dicing and the second dicing, and the electrode substrate 101 does not require the second dicing. By forming this dicing through hole, the first dicing step and the second dicing step can be eliminated. As a result, work efficiency is greatly improved.

  In the third dicing process, a dicing line 308 is drawn in a direction orthogonal to the first and second dicing processes, and the part from the lid to the electrode substrate 101 is cut into individual pieces. However, the process sequence described above is only an example, and for example, the third dicing process may be performed first, and then the first and second dicing processes may be performed.

  In dicing, it is necessary to avoid or suppress chipping at the dicing end face by optimizing the dicing conditions. However, when using a dicing through-hole, it is not necessary to cope with chipping and workability is improved. improves. Alternatively, residual stress during dicing can be avoided, which is also effective for stabilizing device characteristics.

  After the mirror device of the present invention is collectively formed on the substrate through the above steps, it can be divided into pieces. Therefore, the mirror device of the present invention, that is, the switching operation that is repeatedly performed over a long period of time, and the mirror and the mirror support member (beam) are prevented from being damaged by vibration and impact, and foreign matter enters the mirror from the outside on the mirror reflecting surface. It becomes possible to stably manufacture a mirror device having a mechanism for maintaining the reflection characteristics.

  For the mirror device whose opening is opened in the preliminary study example described above, the mirror is placed in a closed space by adding a light-transmitting substrate so as to cover the opening at the wafer stage. (Ie, packaged) to provide the mirror device of the present invention.

It is sectional drawing of the mirror device concerning the preliminary examination example of this invention, and is A-A 'sectional drawing of Fig.2 (a). It is a top view of the mirror device concerning the preliminary examination example of this invention. It is the (a) top view of a mirror substrate concerning the example of preliminary examination of the present invention, and (b) the top view of an electrode substrate. It is sectional drawing which shows operation | movement of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing which shows the state when an impact is added to the mirror device concerning the preliminary examination example of this invention. It is the graph which showed the relationship between the impact acceleration applied to the mirror, the amount of displacement of a mirror, and the maximum principal stress of a beam. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is a top view of the stopper board | substrate of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is a top view of the mirror substrate of the mirror device concerning the preliminary examination example of this invention. It is a top view of the mirror substrate of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning the preliminary examination example of this invention. It is sectional drawing of the mirror device concerning one Example of this invention. It is a figure explaining the dicing process of the mirror device of the present invention. It is a top view of the electrode substrate concerning one Example of this invention. It is a top view of the mirror concerning one Example of this invention.

Explanation of symbols

100: Mirror device 101: Electrode substrate
102, 402: mirror substrate,
103, 403, 123, 745, 842, 303: stopper substrate,
104a, 104b: electrodes,
105, 805, 1205, 1305: stopper step 106, 206, 306, 406, 606, 906, 1006, 1106: mirror,
106a, 206a, 306a, 406a, 906a, 1006a, 1016: mirror reflection surface (reflection surface)
106b, 906b, 1006b: substrate portion, 106c: intermediate oxide film 106d: mirror processing step,
107: Pivot, 108, 908, 1008, 1018: Frame (mirror frame),
109: Mirror back surface step,
531: Common opening, 407: Slope of mirror side surface,
621, 622: cushioning material,
841: spacer,
200, 300, 400, 600, 700, 800, 1200, 1300, 1400, 1500: mirror device,
121a, 121b: power connection pads,
122: positioning hole,
123, 1023: beams, 124a, 124b: wiring,
1223, 1323, 1423: lid,
1324: Receiving part, 1329: Housing
241: dicing groove, 242: dicing through hole,
131, 231, 331, 431, 831: opening, 732, 1432, 1532: first stopper opening, 733, 1433, 1533: second stopper opening,
734, 1434, 1534: first stopper step, 735, 1435, 1535: second stopper step,
306: first dicing line, 307: second dicing line,
308: Third dicing line,
531: common opening,
161: incident light, 162: reflected light,
150a, 150b, 1450, 1550: mirror support protrusions,
1455a, 1455b: roughened areas,
1460a, 1460b: insulating films,
1465: antistatic film,
170: spring for peeling,
180: End of mirror

Claims (5)

In a mirror device having a reflecting surface for reflecting light, including a mirror that is held movably, and switching a direction in which the light is reflected,
A first substrate having an electrode for moving the mirror; a second substrate provided on the upper side of the first substrate; provided on the second substrate and the mirror; A third substrate having an opening to pass through, and a fourth substrate provided above the third substrate and transmitting the light,
The mirror device, wherein a distance between the mirror and the third substrate is larger than a distance between the mirror and the first substrate. In a mirror device having a reflecting surface for reflecting light, including a mirror that is held movably, and switching a direction in which the light is reflected,
A first substrate having an electrode for moving the mirror; a second substrate provided on the upper side of the first substrate; provided on the second substrate and the mirror; A third substrate to transmit,
The mirror device, wherein a distance between the mirror and the third substrate is larger than a distance between the mirror and the first substrate. In a mirror device having a reflecting surface for reflecting light, including a mirror that is held movably, and switching a direction in which the light is reflected,
An electrode having a reflection surface side substrate provided on the reflection surface side of the mirror and having an opening through which the light passes, and an electrode provided on the opposite side of the reflection surface of the mirror and applying a force for moving the mirror A substrate, and a transmission substrate that is provided so as to cover the opening of the reflection surface side substrate and transmits the light,
The distance from the said reflective surface to the said reflective surface side board | substrate is larger than the distance from the said mirror to the said reflective surface side board | substrate, The mirror device characterized by the above-mentioned. In a mirror device having a reflecting surface for reflecting light, including a mirror that is held movably, and switching a direction in which the light is reflected,
A reflective surface-side substrate that is provided on the reflective surface side of the mirror and transmits the light; and an electrode substrate that is provided on the opposite side of the reflective surface of the mirror and has an electrode that applies a force to move the mirror. Prepared,
The distance from the said reflective surface to the said reflective surface side board | substrate is larger than the distance from the said mirror to the said reflective surface side board | substrate, The mirror device characterized by the above-mentioned. In a mirror device comprising a plurality of (three or more) substrates stacked,
One of the plurality of substrates is a mirror substrate having a mirror,
The mirror has a mirror reflection surface and a frame, and is rotatably connected to the mirror substrate and a support member.
The mirror reflecting surface and the frame are arranged on the same surface side of the mirror,
The other one of the plurality of substrates is a first substrate laminated on the side opposite to the mirror reflecting surface with respect to the mirror substrate,
Still another one of the plurality of substrates is a second substrate laminated on the mirror reflecting surface side with respect to the mirror substrate,
The mirror has a plurality (two or more) of stable operation postures,
The mirror is in contact with the first substrate at a plurality of positions opposite to the mirror reflecting surface of the mirror in the stable operation posture;
A distance between the mirror and the first substrate is larger than a distance between the frame and the second substrate;
The second substrate has a first stopper opening and a second stopper opening smaller than the first stopper opening;
The first stopper opening is larger than the mirror;
The second stopper opening is larger than the mirror reflecting surface and smaller than the mirror;
The mirror is disposed in a closed space formed by the plurality of substrates,
At least one of the plurality of substrates is partly or entirely made of a light-transmitting member in order to optically connect a space outside the mirror device and the mirror.

Images